The short answer is: it can be.
The thing is, candida infections aren’t always passed from one person to another – it actually happens way more frequently between partners who’ve already had yeast infections.
But it definitely can and does happen.
What is oral thrush?
Oral thrush is a fungal infection of the mouth that’s most likely to occur in people whose immune system is weakened. That basically means that if you’re a healthy adult, you’re not likely to develop thrush.
Unless you’re engaging in oral sex with an infected person, that is. Or kissing them.
The main symptoms of oral thrush are white, creamy patches in your mouth, usually on the tongue and cheek. Depending on the severity of the condition, you may also experience a burning sensation in the mouth, difficulties swallowing, and even hoarseness, if the infection has spread to your larynx and trachea.
How do I get it?
As we’ve already mentioned, thrush is usually caused by a weakened immune system. That’s because a healthy one keeps the flora – the bacteria and fungi in your mouth – in balance.
As your immune system is weakened – for instance, if you’ve got AIDS or cancer, or if you’ve been taking antibiotics for longer periods – a certain species of fungus in your mouth, known as candida albicans, grows disproportionately, eventually leading to oral thrush.
This disproportionate growth may also be caused by other factors: improper oral hygiene, wearing dentures, smoking or taking steroids can all cause thrush. As you can see, all these factors perturb the natural balance of organisms in your mouth, favoring candida overgrowth.
What about sex?
It’s possible that you can get oral thrush from having sex with an infected person, but that’s not always the case.
You can get oral thrush from kissing a person with thrush, or from performing oral sex on a person having vaginal/penile candidiasis. Similarly, you can transmit oral thrush by engaging in any of the acts mentioned above.
The risk is that much greater if you’re having a stable partner who’s already infected – you’ll basically be re-infecting each other in an endless loop.
So what should I do?
It’s easy: get treated, stop having sex, and get your partner treated again.
You should consult your doctor if you think you might have gotten candida from your partner, and you should definitely encourage them to get treated, too. Refraining from unprotected oral sex during the course of the treatment is essential.
Conclusion
Oral thrush may be passed on from partner to partner during sexual intercourse, but that’s not necessarily the case. However, if you’ve got it, it’s best to get your partner treated, too. This way you’ll prevent an unpleasant situation of back and forth re-infection, and you’ll speed up the healing time.
Resources:
http://www.mayoclinic.org/diseases-conditions/oral-thrush/basics/definition/con-20022381
https://en.wikipedia.org/wiki/Oral_candidiasis
http://www.nhs.uk/conditions/Oral-thrush—adults/Pages/Introduction.aspx
http://emedicine.medscape.com/article/969147-clinical
http://www.dummies.com/relationships/sex/stds-a-look-at-candidiasis/
http://www.colgate.com/en/us/oc/oral-health/conditions/hiv-aids-and-stds/article/stds-of-the-mouth-and-how-to-avoid-them-0515
http://www.bustle.com/articles/69020-what-is-candida-how-yeast-infections-can-be-sexually-transmitted-and-what-you-can-do